Excirolana braziliensis is a coastal intertidal isopod with a broad distribution spanning the Atlantic and Pacific tropical and temperate coasts of the American continent. Two separate regional studies (one in Panama and one in Chile) revealed the presence of highly genetically divergent lineages, implying that this taxon constitutes a cryptic species complex. The relationships among the lineages found in these two different regions and in the rest of the distribution, however, remain unknown. To better understand the phylogeographic patterns of E. braziliensis, we conducted phylogenetic analyses of specimens from much of its entire range. We obtained DNA sequences for fragments of four mitochondrial genes (16S rDNA, 12S rDNA, COI, and Cytb) and also used publicly available sequences. We conducted maximum likelihood and Bayesian phylogenetic reconstruction methods. Phylogeographic patterns revealed the following: (1) new highly divergent lineages of E. braziliensis; (2) three instances of Atlantic–Pacific divergences, some of which appear to predate the closure of the Isthmus of Panama; (3) the distributional limit of highly divergent lineages found in Brazil coincides with the boundary between two major marine coastal provinces; (4) evidence of recent long‐distance dispersal in the Caribbean; and (5) populations in the Gulf of California have closer affinities with lineages further south in the Pacific, which contrasts with the closer affinity with the Caribbean reported for other intertidal organisms. The high levels of cryptic diversity detected also bring about challenges for the conservation of this isopod and its fragile environment, the sandy shores. Our findings underscore the importance of comprehensive geographic sampling for phylogeographic and taxonomical studies of broadly distributed putative species harboring extensive cryptic diversity.

Macrofauna of sheltered and pocket beaches located in embayments, estuaries or landward of protective reefs has not been adequately assessed in beach ecology. In this setting, the concurrent role of large‐scale morphodynamics and wave‐exposure gradients in shaping biological patterns is still uncertain. To examine variations in community descriptors and the influence of physical factors on macrofauna, 12 sandy beaches on five islands within Sepetiba Bay (SE Brazil) were characterized in terms of beach morphodynamics and dimensions (length and width), such as geographical position relative to the bay mouth. A total of 80 species were collected and identified. Community descriptors of macrofauna responded to morphodynamics and exposure gradients. Increases in species richness, and abundance, from harsh reflective (coarse sands, steep slopes) to benign dissipative (fine sands, gentle slopes) beaches, and from the bay mouth (exposed beaches) towards the inner bay (sheltered beaches) were observed. Mollusks were the most abundant macrofaunal group, followed by crustaceans and polychaetes. Crustaceans dominated the beaches near the bay mouth, whereas mollusks were more abundant on the beaches farther from the bay mouth. Canonical correspondence analysis showed that the degree of exposure, distance from the bay mouth, beach index, and beach length and width significantly affected the macrofauna distribution and abundance, creating an environmental gradient along Sepetiba Bay. Differences in macrofauna composition among the beaches studied were associated with beach length and width. In this sense, spatial variation of macrofauna among beaches can be a function of intertidal area. These results indicate that community characteristics in the sandy beaches studied are affected by several physical characteristics, but also by other factors that are affected by coastal processes.

1. In addition to being threatened by habitat loss derived from deforestation and urbanisation, fireflies are further deeply impacted by light pollution, which impairs their unique use of light signals to communicate and track females. The impact of stressors that can lead to declines in firefly populations is poorly known in the southern hemisphere, including the Atlantic Forest where they are especially diverse, associated with lack of knowledge about their distributions.2. Here, we model the potential distribution of the tracker ghost firefly Amydetes fastigiata and investigate whether light pollution, urbanisation and deforestation are increasing over time in this area.3. We found that light pollution is the stressor with the most prominent increase rates over its distribution. Light pollution is significantly increasing in extent and intensity over time, outpassing urbanisation and deforestation which increased at lower rates. Protected areas successfully buffer effects of urbanisation and deforestation, but are incapable to halt the spread of light pollution.4. Increasing light pollution is especially concerning due to the spotlighting behaviour of A. fastigiata to track females through the night, which is imperilled by overshadowing lights. Light pollution trends are increasing fast and should be considered as a significant stressor even within protected areaswhich calls for a reform in regional conservation policies and designation of new areas to be prioritised.5. We presented a framework for the evaluation of threat rates based on species distribution models that can foster future research and assess vulnerabilities of important species facing global change.

The population biology and secondary production of the bivalves Anomalocardia brasiliana (Gmelin, 1791) and Diplodonta punctata (Say, 1822) were studied on a sheltered beach on the southeast coast of Brazil (1) A. brasiliana occupied mainly the upper levels, whereas D. punctata occupied the lower level of the beach; (2) total abundance, growth rate, and production were higher for A. brasiliana; and (3) mortality and turnover rate were higher for D. punctata. The differences in growth, mortality, and production parameters may be associated with a difference in the species' abilities to exploit resources.